Sundial Patents

There are a number of different kinds of patents. The normal
patent granted for the intellectual property of the idea, a Design
patent (D) is
granted for the appearance of the end item, and a Plant Patent (PP) is
for
the genetic makeup of the plant.

Patents are categorized by class with similar patents all in the
same class/sub
class. The Sunnyvale, CA public patent library has their patents
filed
by Class rather than by patent number like the other patent
libraries.
BI (Before Internet) this made doing patent searches much easier.
In the table below you can click on the linked class numbers to search
that
class. Even the very old patents have the class number searchable
at
the USPTO. 33/270
is the main sundial class and 33/269 and 33/268 are related classes.

The newer US patents have a lot more searchable and also have links
to
thepatents they cite as prior art.

About 95% of all these relate to a sun dial combined with a
magnetic
comapss. Maybe 5 dozen patents.

Class 968/415
Horology &
Timepieces using the Position of the Sun, Moon, or Stars (Devices for
Fixing the Place and Time by Astronomical Observations G01C 21/00)
[G04B 49/00] & Sundials (normal dials subclass 147) [G04B
49/02]